What infections can be transmitted by ticks? - briefly
Ticks transmit bacterial diseases such as Lyme disease, Rocky Mountain spotted fever, ehrlichiosis, and anaplasmosis, viral illnesses like tick‑borne encephalitis and Powassan virus, and the protozoan infection babesiosis. These agents are introduced during the tick’s blood meal and may cause severe systemic illness if not promptly treated.
What infections can be transmitted by ticks? - in detail
Ticks serve as vectors for a broad spectrum of pathogens that cause human disease. The most clinically significant agents fall into bacterial, viral, and protozoal categories.
Bacterial agents transmitted by ticks include:
- Borrelia burgdorferi – the cause of Lyme disease; prevalent in North America, Europe, and parts of Asia; early symptoms comprise erythema migrans, fever, fatigue, and headache; later stages may involve arthritis, carditis, and neuroborial manifestations.
- Anaplasma phagocytophilum – responsible for human granulocytic anaplasmosis; transmitted primarily by Ixodes scapularis and Ixodes pacificus; presents with fever, leukopenia, thrombocytopenia, and elevated liver enzymes.
- Ehrlichia chaffeensis – agent of human monocytic ehrlichiosis; spread by the lone‑star tick (Amblyomma americanum); clinical picture includes fever, rash, hepatitis, and leukopenia.
- Rickettsia rickettsii – causes Rocky Mountain spotted fever; vectors are Dermacentor species; hallmark signs are high fever, headache, and a maculopapular rash that may involve the palms and soles.
- Rickettsia parkeri – transmitted by Amblyomma maculatum; produces a milder spotted fever with eschar formation at the bite site.
- Francisella tularensis – the agent of tularemia; Dermacentor and other hard ticks can spread the bacterium; disease manifests as ulceroglandular, pneumonic, or typhoidal forms.
- Coxiella burnetii – occasionally transmitted by ticks, leading to Q fever; infection may be asymptomatic or cause febrile illness with hepatitis.
Protozoal pathogens include:
- Babesia microti – causes babesiosis; Ixodes scapularis is the principal vector; symptoms range from asymptomatic infection to severe hemolytic anemia, especially in immunocompromised patients.
- Babesia divergens – found in Europe; transmitted by Ixodes ricinus; produces a clinical picture similar to B. microti infection.
- Theileria spp. – rare human cases reported; transmitted by Haemaphysalis ticks; can lead to febrile illness with hepatosplenomegaly.
Viral agents carried by ticks comprise:
- Powassan virus – a flavivirus transmitted by Ixodes species; neuroinvasive disease may develop within days of the bite, causing encephalitis or meningitis.
- Tick‑borne encephalitis (TBE) virus – prevalent in Europe and Asia; transmitted by Ixodes ricinus and Ixodes persulcatus; biphasic illness with initial flu‑like symptoms followed by meningo‑encephalitis.
- Colorado tick fever virus – a coltivirus spread by Dermacentor andersoni; produces a self‑limited febrile illness with rash and thrombocytopenia.
- Heartland virus – a phlebovirus transmitted by Amblyomma americanum; presents with fever, leukopenia, and elevated liver enzymes.
- Bourbon virus – another phlebovirus associated with lone‑star tick bites; clinical features include fever, thrombocytopenia, and elevated transaminases.
Emerging and less common agents continue to be identified, underscoring the need for surveillance. Diagnosis relies on clinical suspicion, epidemiologic exposure, and laboratory testing specific to each pathogen. Prompt antimicrobial or antiviral therapy, when indicated, reduces morbidity and mortality. Prevention focuses on personal protective measures and tick control in endemic habitats.